Компьютерное моделирование ветровых нагрузок на высотные здания

The paper presents the results of numerical simulation of wind pressure on high rise buildings being under construction and planned in Yekaterinburg city (Russia). Simulation is performed in the program ANSYS. The simulated building is placed in a domain that is the numerical analogue of wind tunnel. Domain sizes are chosen in such a way that simulated buildings do not affect the flow of air on its boundaries. Shear stress transport (SST) turbulence model is used. In order to validate the numerical model the paper presents the results of experimental study and numerical simulation of external air flow around the cylindrical body with the diameter of 8 mm, placed on the way of free submerged jet of air. The cylinder which has simple geometry form was used due to the need to achieve the generality of the outcomes. A comparison of the results of calculation of wind pressure with the experimental data blasting building models in wind tunnels is done.В статье представлены результаты численного моделирования задачи определения ветровых давлений на строящиеся или проектируемые в г. Екатеринбурге (Россия) высотные здания. Задача решается в пакете ANSYS. Моделируемое здание и его окружение помещаются в домен, который является численным аналогом ветровой трубы. Размеры домена назначаются таким образом, чтобы объекты, входящие в домен, не влияли на движение воздуха у внешних границ домена. Для расчета используется модель SST. Для проверки правильности численной модели приводится сравнение результатов расчета с экспериментальными данными обдувки цилиндра диаметром 8 мм. Такая модель простой формы выбрана для удобства сравнения. Приведено сравнение численных результатов расчета давлений ветра на высотные здания с результатами обдувки в ветровых трубах

Thermal Conductivity of Methane-Hydrate

The thermal conductivity of the methane hydrate CH4 (5.75 H2O) was measured in the interval 2-140 K using the steady-state technique. The thermal conductivity corresponding to a homogeneous substance was calculated from the measured effective thermal conductivity obtained in the experiment. The temperature dependence of the thermal conductivity is typical for the thermal conductivity of amorphous solids. It is shown that after separation of the hydrate into ice and methane, at 240 K, the thermal conductivity of the ice exhibits a dependence typical of heavily deformed fine-grain polycrystal. The reason for the glass-like behavior in the thermal conductivity of clathrate compounds has been discussed. The experimental results can be interpreted within the phenomenological soft-potential model with two fitting parameters.Comment: 13 pages, 3 figure

Thermal conductivity of solid krypton with methane admixture

The thermal conductivity of CH₄–Kr solid solutions is investigated at CH₄ concentrations 0.2–5.0% in the temperature range 1.8–40 K. It is found that the temperature dependence of the thermal conductivity has features typical of resonance phonon scattering. The analysis of the experimental results shows that the main contribution to the impurity-caused scattering of phonons is made by the scattering on rotational excitations of the nuclear spin T-species of CH₄ molecules. The phonon–rotation interaction parameter is estimated

Computer simulation-based analysis of wind load effect on structural capacity of skywalk between Hyatt Regency hotel and multipurpose building complex Iset Tower in Ekaterinburg

This article contains a computer - aided analysis of bearing capacity under wind load for a standard attachment fixture which one is most frequently used for mounting transparent structures. The analysis results of peak positive and negative wind loads acting on the enveloping structure are presented. The stress-strain state of the skywalk facade fixture unit in the elastic strain stage is analyzed. Maximal values of force influence on the plastic deformation of the fixture unit components arise. They are determined on the basis of a nonlinear analysis. The object of the research is a skywalk between the Hyatt Regency hotel building and the Iset Tower high-rise building in Ekaterinburg that is being designed currently. Simulation models and computational experiments were made in ANSYS CFX software complex. © Published under licence by IOP Publishing Ltd.The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0006

Properties of solid hydrogen doped by heavy atomic and molecular impurities

Using powder x-ray diffraction we studied the structural characteristics of normal and para hydrogen crystals doped with Ar, Kr, N₂, and O₂ impurities over the range from 5 K to the melting point of the hydrogen matrix. It has been established that in spite of very low solubility of the dopants in solid hydrogen, these impurities appreciably affect the structural characteristics. In particular, only nitrogen impurities do not change the molar volume of the matrix, the other three make the matrix expand. The Ar and Kr impurities also change the c/a ratio of the hcp matrix. The fact that both Ar and O₂ have smaller molar volumes than hydrogen may be treated as evidence that these impurities form van der Waals complexes with the hydrogen lattice environment

Activation transport under quantum Hall regime in HgTe-based heterostructure

We have measured the temperature (2.9 K < T < 50 K) and magnetic field (0 T < B < 9 T) dependences of longitudinal and Hall resistivities for HgCdTe/HgTe/HgCdTe system with HgTe quantum well width of 20.3 nm. The activation analysis of the experimental magnetoresistivity traces has been used as a quantitative tool to probe inter-Landau level distances. The activation energies were determined from the temperature dependence of the longitudinal resistivity in the regions of quantized Hall plateaus (for the filling factors ν of 1, 2 and 3) and the indications of the large values of the g factor ≅ 30–75 were found